In recent years, capacity of a power supply device has been increased in vehicles having a motor as a driving source mounted thereon such as hybrid vehicles and electric vehicles, in order to improve acceleration performance and travel performance such as a distance that can be traveled. There have been proposed structures including a plurality of power storage units as means for increasing capacity of a power supply device.
For example, Japanese Patent Laying-Open No. 2003-209969 (Patent Document 1) discloses a power supply control system including a plurality of power supply stages. This power supply control system includes a plurality of power supply stages which are connected in parallel to one another and supply DC power to at least one inverter. Each power supply stage includes a battery and a boost/buck DC-DC converter having a DC chopper circuit.
In this power supply control system, the plurality of power supply stages are controlled such that the plurality of batteries included in the plurality of power supply stages, respectively, are charged and discharge evenly to maintain output voltage to the inverter (see Patent Document 1).
Patent Document 1: Japanese Patent Laying-Open No. 2003-209969